Thiamine and phosphate esters concentrations in whole blood and serum of patients with alcohol use disorder: a relation with cognitive deficits.

Background: In this study, we investigated (1) the effect of chronic and excessive alcohol consumption on whole blood (WB) and serum concentrations of thiamine and its metabolites after supplementation, and (2) the relationship between the perturbations of thiamine metabolism and neuropsychological abilities.Methods: WB and serum samples were collected in patients with Alcohol Use Disorder (AUD) and in healthy control subjects (after oral thiamine supplementation, or without supplementation). Thiamine (Th), thiamine monophosphate (TMP) and thiamine diphosphate (TDP) were quantified. The Brief Evaluation of Alcohol-Related Neuropsychological Impairments (BEARNI) and the Montreal Cognitive Assessment (MoCA) were performed by each AUD participant. Based on the BEARNI score, two groups of AUD patients were studied: AUD patients with no or mild cognitive impairment (AUD COG+), and AUD patients with moderate-to-severe cognitive impairment (AUD COG-).Results: In WB, Th concentrations were significantly higher, and percentages of phosphate esters of thiamine were significantly lower in AUD COG- patients compared to controls. In serum, Th concentrations were significantly higher in AUD COG- patients compared to controls. The percentage of Th in serum was significantly higher in AUD COG- patients compared to AUD COG+ patients, and to the groups of controls. When adjusted on education level, the percentage of Th in serum in AUD patients negatively correlated with the scores at BEARNI and MoCA, and Th concentration in serum negatively correlated with MoCA.Conclusions: These data support an impairment of metabolism and/or distribution of thiamine in AUD patients, and a relationship with the development of alcohol-related cognitive deficits.

Nicotinamide Deficiency in Primary Open-Angle Glaucoma.

Purpose: To investigate the plasma concentration of nicotinamide in primary open-angle glaucoma (POAG). Methods: Plasma of 34 POAG individuals was compared to that of 30 age- and sex-matched controls using a semiquantitative method based on liquid chromatography coupled to high-resolution mass spectrometry. Subsequently, an independent quantitative method, based on liquid chromatography coupled to mass spectrometry, was used to assess nicotinamide concentration in the plasma from the same initial cohort and from a replicative cohort of 20 POAG individuals and 15 controls. Results: Using the semiquantitative method, the plasma nicotinamide concentration was significantly lower in the initial cohort of POAG individuals compared to controls and further confirmed in the same cohort, using the targeted quantitative method, with mean concentrations of 0.14 µM (median: 0.12 µM; range, 0.06-0.28 µM) in the POAG group (-30%; P = 0.022) and 0.19 µM (median: 0.18 µM; range, 0.08-0.47 µM) in the control group. The quantitative dosage also disclosed a significantly lower plasma nicotinamide concentration (-33%; P = 0.011) in the replicative cohort with mean concentrations of 0.14 µM (median: 0.14 µM; range, 0.09-0.25 µM) in the POAG group, and 0.19 µM (median: 0.21 µM; range, 0.09-0.26 µM) in the control group. Conclusions: Glaucoma is associated with lower plasmatic nicotinamide levels, compared to controls, suggesting that nicotinamide supplementation might become a future therapeutic strategy. Further studies are needed, in larger cohorts, to confirm these preliminary findings.